Power control method for image forming apparatus to selectively control switching circuit unit to manage power supply according to last known power status when power is resumed after an abnormal power failure

Abstract

An image forming apparatus and a power control method thereof are provided. The image forming apparatus includes: an image forming unit which forms an image; a power supply which supplies operating power for the image forming apparatus; a switching circuit unit which switches to selectively supply the operating power; a memory unit which stores information about power status of the switching circuit unit; and a controller which outputs a power control signal for controlling a switching operation of the switching circuit unit in accordance with the information about the power status stored in the memory unit if power is abnormally shut off and then supplied again from the power supply to the switching circuit unit. With this, the image forming apparatus operates in a last power status, so that power can be prevented from being wastefully consumed or data can be prevented from being lost.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 an image forming unit which forms an image; 
 a power supply which supplies operating power for the image forming apparatus; 
 a switching circuit unit which switches to selectively supply the operating power; 
 a memory unit which stores information about power status of the switching circuit unit; 
 a controller which outputs a power control signal to control a switching operation of the switching circuit unit in accordance with the information about the power status stored in the memory unit if power is abnormally shut off and then supplied again from the power supply to the switching circuit unit; and 
 a key input unit through which a user input related to supply of the operating power is received, 
 wherein the switching circuit unit comprises a first switch turned on/off in response to the user input into the key input unit, and a second switch turned on/off in response to the power control signal of the controller, 
 wherein the controller reads the information about the power status from the memory unit and outputs the power control signal for turning on/off the second switch to match with the read information about the power status if power is supplied to the switching circuit unit without a user input to the first switch and the first switch is in an “off” status, and 
 wherein the second switch is coupled between a general output port of the controller and the first switch. 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein the controller initializes the image forming apparatus and monitors the user input to the first switch if the read information about the power status is “on”. 
     
     
       3. The image forming apparatus according to  claim 2 , the controller records the power status of the switching circuit unit as “off” in the memory unit and controls the switching circuit unit to shut off the operating power if the user input to the first switch is received. 
     
     
       4. The image forming apparatus according to  claim 3 , wherein the controller backs up data of the image forming apparatus, and controls the switching circuit unit to shut off the operating power. 
     
     
       5. The image forming apparatus according to  claim 1 , wherein the controller outputs a power control signal for turning off the switching circuit unit if the read information about the power status is “off”. 
     
     
       6. The image forming apparatus according to  claim 1 , wherein the controller records the power status of the switching circuit unit as “on” in the memory unit if power is supplied to the switching circuit by the user input to the first switch. 
     
     
       7. The image forming apparatus according to  claim 6 , wherein the controller initializes the image forming apparatus, and monitors the user input to the first switch. 
     
     
       8. The image forming apparatus according to  claim 7 , wherein the controller records the power status of the switching circuit unit as “off” in the memory unit if receiving the user input to the first switch, and controls the switching circuit unit to shut off the operating power. 
     
     
       9. The image forming apparatus according to  claim 8 , wherein the controller backs up data of the image forming apparatus, and controls the switching circuit unit to shut off the operating power. 
     
     
       10. The image forming apparatus according to  claim 1 , wherein the memory unit comprises a non-volatile memory. 
     
     
       11. A power control method of an image forming apparatus comprising a power supply for supplying operating power, and a switching circuit unit for switching to selectively supply the operating power, and a controller, the power control method comprising:
 supplying power from the power supply to the switching circuit unit; 
 reading information about power status from a memory unit storing information about power status of the switching circuit unit if power is abnormally shut off and then supplied again to the switching circuit unit; and 
 outputting a power control signal from the controller to control a switching operation of the switching circuit unit in response to the read information about the power status, 
 wherein the switching circuit unit comprises a first switch turned on in response to a user input related to supply of the operating power, and a second switch turned on/off in response to the power control signal of the controller, 
 wherein if power is supplied to the switching circuit unit without the user input to the first switch and the first switch is in an “off” status, the outputting of the power control signal comprises outputting the power control signal for turning on/off the second switch to match with the read information about the power status, 
 wherein the second switch is coupled between a general output port of the controller and the first switch. 
 
     
     
       12. The power control method according to  claim 11 , further comprising
 initializing the image forming apparatus; and 
 monitoring the user input to the first switch of the switching circuit unit, 
 if the read information about the power status is “on”. 
 
     
     
       13. The power control method according to  claim 12 , further comprising
 receiving the user input to the first switch; 
 recording the power status of the switching circuit unit as “off” in the memory unit; and 
 outputting the power control signal to shut off the operating power. 
 
     
     
       14. The power control method according to  claim 13 , further comprising backing up data of the image forming apparatus. 
     
     
       15. The power control method according to  claim 11 , wherein the outputting of the power control signal comprises outputting the power control signal for turning off the switching circuit unit if the read information about the power status is “off”. 
     
     
       16. The power control method according to  claim 11 , further comprising recording the power status of the switching circuit unit as “on” in the memory unit if power is supplied to the switching circuit unit by the user input to the first switch. 
     
     
       17. The power control method according to  claim 16 , further comprising
 initializing the image forming apparatus; and 
 monitoring the user input to the first switch. 
 
     
     
       18. The power control method according to  claim 17 , further comprising
 recording the power status of the switching circuit unit as “off” in the memory unit if receiving the user input to the first switch to shut off the operation power as a monitoring result; and 
 controlling the switching circuit unit to shut off the operating power. 
 
     
     
       19. The power control method according to  claim 18 , further comprising backing up data of the image forming apparatus. 
     
     
       20. The power control method according to  claim 11 , wherein the memory unit comprises a non-volatile memory. 
     
     
       21. A power control method of an image forming apparatus comprising a power supply to supply operating power, a key input unit for receiving a user input related to supply of the operating power, a switching circuit unit for switching to selectively supply the operating power, and a controller which outputs a power control signal to control the switching operation of the switching circuit unit, the power control method comprising:
 supplying power from the power supply to the switching circuit unit; 
 recording a power status of the switching circuit unit as “on” in a memory unit if power is supplied to the switching circuit unit because the key input unit receives the user input requesting that power be supplied from the power supply to the switching circuit unit; and 
 initializing the image forming apparatus, 
 wherein the switching circuit unit comprises a first switch turned on in response to a user input related to supply of the operating power, and a second switch turned on/off in response to the power control signal of the controller, 
 wherein if power is supplied to the switching circuit unit without the user input to the first switch and the first switch is in an “off” status, the outputting of the power control signal comprises outputting the power control signal for turning on/off the second switch to match with the read information about the power status, and 
 wherein the second switch is coupled between a general output port of the controller and the first switch. 
 
     
     
       22. The power control method according to  claim 21 , further comprising:
 supplying power to the controller as the power is supplied to the switching circuit unit, and booting up the controller, 
 wherein the image forming apparatus is initialized by the booted-up controller. 
 
     
     
       23. The power control method according to  claim 21 , further comprising
 monitoring the user input to the key input unit; 
 recording the power status of the switching circuit unit as “off” in the memory unit if receiving the user input to the first switch to shut off the operating power as a monitoring result; and 
 outputting a power control signal to shut off the operating power. 
 
     
     
       24. The power control method according to  claim 23 , further comprising backing up data of the image forming apparatus.